TCB Publications - Abstract

TCB Publications - Abstract

Fangqiang Zhu, Emad Tajkhorshid, and Klaus Schulten. Theory and simulation of water permeation in aquaporin-1. Biophysical Journal, 86:50-57, 2004. (PMC: 1303818)

ZHU2004 The paper starts with a detailed discussion of the difference between osmotic permeability $p_f$ and diffusion permeability $p_d$ of single- file water channels, demonstrating that the $p_f/p_d$ ratio corresponds to the number of effective steps a water molecule needs to take to permeate the channel. While $p_d$ can be directly obtained from equilibrium molecular dynamics simulations, $p_f$ must be determined from simulations in which a chemical potential difference of water has been established on the two sides of the channel. In light of this, we suggest here a method to induce in molecular dynamics simulations a hydrostatic pressure difference across the membrane, from which $p_f$ can be measured. Simulations using this method are performed on aquaporin-1 channels in a lipid bilayer, resulting in a calculated $p_f$ of 7.1$\times$10$^{-14}$cm$^3$/s, which is in close agreement with observation. Using a previously determined $p_d$ value, we conclude that $p_f/p_d$ for aquaporin-1 measures about 12. This number is explained in terms of channel architecture and conduction mechanism.

Download Full Text

The manuscripts available on our site are provided for your personal use only and may not be retransmitted or redistributed without written permissions from the paper's publisher and author. You may not upload any of this site's material to any public server, on-line service, network, or bulletin board without prior written permission from the publisher and author. You may not make copies for any commercial purpose. Reproduction or storage of materials retrieved from this web site is subject to the U.S. Copyright Act of 1976, Title 17 U.S.C.

Download full text: PDF (243.4KB)